The island of Yonaguni, near Okinawa, Japan has long been a favorite diving spot for swimmers try to get a glance of the numerous hammerhead sharks that swim there. However, in 1995 underwater explorer Kihachirou Aratake found a very large, strange structure under the water. Lying about 60 feet deep, the structure appeared to be man-made. Large steps could be seen, blocks of rock cut at right angles and smoothed. The discovery would send shock waves through the archaeological world.

Japan's Underwater Pyramids or Ruins as they have become to be known are a mystery. In all, around eight sites have been discovered. There are certain features that are very hard to dismiss as natural occurrences. Such as a large, semi-circular structure that almost looks like a park bench. Then there is a large head which appears to have hair and a head dress carved into it. There are also numerous round holes carved into the rock, including some that look as though they were made to support large wooden poles. Again, these are just hard to dismiss, including this head with eyes carved out of it. As stated, the structures are lying on the seabed, around 60 to 100 feet below the surface. The last time that these areas were not covered by the ocean was between approximately 8 to 12 thousand years ago, during the last ice age when much of the sea was caught up in the ice caps.At the time Yonaguni formed a landbridge with Taiwan, leading many to speculate that the area is part of the lost continent of Mu, or Lemuria.

Cleopatra's Palace in Alexandria (Egypt)

Off the shores of Alexandria, the city of Alexander the Great, lies what is believed to be the ruins of the royal quarters of Cleopatra. A team of marine archaeologists led by Frenchman Franck Goddio made excavation on this ancient city from where Cleopatra, the last queen of the Ptolemies, ruled Egypt. Historians believe this site was submerged by earthquakes and tidal waves more than 1,600 years ago.

The excavations concentrated on the submerged island of Antirhodus. Cleopatra is said to have had a palace there. Other discoveries include a well-preserved shipwreck and red granite columns with Greek inscriptions. There were also founded two statues which were lifted out of the harbor. One was a priest of the goddess Isis; the other a sphinx whose face is said to represent Cleopatra's father, King Ptolemy XII. The artifacts were returned to their silent, because the Egyptian Government says it wants to leave most of them in place to create an underwater museum

2 HUGE UNDERWATER CITIES FOUND IN INDIA

Lost city 'could rewrite history'

By BBC News Online's Tom Housden

The remains of what has been described as a huge lost city may force historians and archaeologists to radically reconsider their view of ancient human history.

Marine scientists say archaeological remains discovered 36 meters (120 feet) underwater in the Gulf of Cambay off the western coast of India could be over 9,000 years old.

The vast city - which is five miles long and two miles wide - is believed to predate the oldest known remains in the subcontinent by more than 5,000 years.

The site was discovered by chance last year by oceanographers from India's National Institute of Ocean Technology conducting a survey of pollution.

Using sidescan sonar - which sends a beam of sound waves down to the bottom of the ocean they identified huge geometrical structures at a depth of 120ft.

Debris recovered from the site - including construction material, pottery, sections of walls, beads, sculpture and human bones and teeth has been carbon dated and found to be nearly 9,500 years old.

Lost civilization

The city is believed to be even older than the ancient Harappan civilization, which dates back around 4,000 years.

Marine archaeologists have used a technique known as sub-bottom profiling to show that the buildings remains stand on enormous foundations.

Author and film-maker Graham Hancock - who has written extensively on the uncovering of ancient civilizations - told BBC News Online that the evidence was compelling:

"The [oceanographers] found that they were dealing with two large blocks of apparently man made structures.

"Cities on this scale are not known in the archaeological record until roughly 4,500 years ago when the first big cities begin to appear in Mesopotamia.

"Nothing else on the scale of the underwater cities of Cambay is known. The first cities of the historical period are as far away from these cities as we are today from the pyramids of Egypt," he said.

"There's a huge chronological problem in this discovery. It means that the whole model of the origins of civilization with which archaeologists have been working will have to be remade from scratch," he said.

However, archaeologist Justin Morris from the British Museum said more work would need to be undertaken before the site could be categorically said to belong to a 9,000 year old civilization.

"Culturally speaking, in that part of the world there were no civilizations prior to about 2,500 BC. What's happening before then mainly consisted of small, village settlements," he told BBC News Online.

Dr Morris added that artifacts from the site would need to be very carefully analyzed, and pointed out that the C14 carbon dating process is not without its error margins.

It is believed that the area was submerged as ice caps melted at the end of the last ice age 9-10,000 years ago